This one is most likely a PH-260 model made especially for US Army airforce. I say 'most likely', because an almost identical model was apparently made also for civil use as 'Model-50', altough I have not yet seen one. Unfortunately the model badge from the back of my meter has fallen off, so I cannot be 100% sure which one this is. But there are two hints that this could be the military model. First, although it has mostly worn off, there are still patches of black paint on the metal ring (it was painted black in military models). And secondly, the case is actually not made for Model-50, but Model-40. Both models had identical cases, except that Model-40 had the model name carved on the case. It is hard to believe, that DeJur would have made a meter that was sold as Model-50, but has Model-40 marking in it's case. But for the military production they may have used them.

This one looks like it has been used by the army, but is otherwise complete. It came from Suffolk, UK, with its leather case.